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High on the Chajnantor plateau in the Chilean Andes,
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the first antennas of the Atacama Large Millimeter/submillimeter Array
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or ALMA for short, move in unison.
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Work progresses at a frantic pace in this ambitious project,
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which, in a few years from now, will consist of 66 antennas, working together at an altitude of 5000 metres.
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Once completed, ALMA will enable astronomers to study the cold Universe in unprecedented detail.
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This is the ESOcast!
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Cutting-edge science and life behind the scenes of ESO, the European Southern Observatory.
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Exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske.
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Hello and welcome to the ESOcast.
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In this episode we are going to visit the ALMA observatory in the Atacama Desert in Chile.
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Here, ESO, together with its international partners,
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is building what will become the world´s largest astronomical facility.
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ALMA will observe the Universe at millimetre and submillimetre wavelengths.
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This will allow astronomers to study both very cold objects as well as very distant objects in the early Universe.
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Now because such observations are disturbed by water vapour in the atmosphere,
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ALMA’s being built on one of the driest places on Earth, the Chajnantor plateau at an altitude of 5000 metres,
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which also makes it one of the highest astronomy sites in the world.
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ALMA will be operated at two distinct sites:
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First, there’s the Array Operations Site up on the plateau where the antennas are actually located,
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and then, further down, there’s the Operations Support Facility.
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Constructing the ALMA observatory in the arid Atacama desert and at such high altitude is no easy undertaking.
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Before the antennas are brought to the high site they must be assembled at the Operations Support Facility or OSF.
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Located at 2900 metres altitude,
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the OSF also serves as the control centre for the antenna array, which is located at the high site.
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With majestic volcanoes looming in the distance, engineers are busy integrating and verifying the numerous parts of the antennas
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and by now, many antennas at various assembly stages can be found at the OSF.
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Each new antenna must meet very strict requirements.
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The surface of each dish is accurate to much less than the thickness of a sheet of paper,
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and the antennas can be pointed precisely enough to pick out a golf ball at a distance of 15 km.
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In many ways the OSF has become the heart of the ALMA project.
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This is where the staff live during their shifts and where much of the daily routine is going on.
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There are lots of meetings between various groups of scientists and engineers
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and there are even scientific conferences that are being held at this remote location.
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The OSF also houses the two transporters that are used to move the antennas.
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So with the scientists and engineers assembling and testing the antennas and conducting the operations at the high site,
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the OSF has become a rather busy and vibrant place.
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Scientists and engineers test the ultimate performance of the complex system.
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Pointing and holography tests are performed around the clock
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and the experts make sure that only antennas fulfilling the tough ALMA specifications get the green light.
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After an antenna has successfully passed all tests at the OSF,
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the time has come to move it up to the Array Operations Site, which lies at an altitude of 5000 metres.
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This was successfully done for the first time in September 2009.
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A giant custom-designed transporter is used to bring up the antenna.
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As each antenna weighs about 100 tons, this is a delicate task that requires the utmost attention.
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Two transporters are available and they are also used to move the antennas to different positions to reconfigure the ALMA array.
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The Array Operations Site is a place of extremes,
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with strong winds, low temperatures and a thin atmosphere.
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However, because of its extreme dryness and altitude,
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the site offers excellent conditions for observing the submillimetre radio waves for which ALMA was designed.
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In addition, Chajnantor offers plenty of space.
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And that’s needed because, in its most extended configuration, the array of antennas measures 16 kilometres across.
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Despite the harsh conditions, work is ongoing to prepare the plateau for the antennas.
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A road network has been built and the workers are busy with various tasks to finish the construction work.
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All of the 192 antenna foundations have been completed and some of them are already in use.
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There is also the technical building, which will eventually be used to receive the data from the antennas
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to further process and then to transmit them down to the OSF.
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Now as the number of antennas on the high site is constantly increasing,
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the project is moving into a new and important phase: that of Commissioning and Science Verification.
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Down at the OSF control room the tension is high as the tests are performed.
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The Commissioning and Science Verification process is intended to confirm
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that the whole facility has been taken from the stage where it was a collection of very complex parts
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into an instrument capable of producing images and measurements with exquisite sensitivity and precision.
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The antennas are placed at different positions within the array
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to make sure that all of their basic functions work correctly at different baselines.
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Currently, the antennas are located at the centre of the site,
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using antenna stations that will eventually form the so-called Atacama Compact Array.
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ALMA is rapidly moving forward and it holds a bright future for many areas of astronomy.
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For example, it will provide us with some unique insight into how stars and planets form,
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and it will be one of the premier tools to study the first stars and galaxies in the early and distant Universe.
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And so, many of us astronomers simply can't wait to get their hands on to this fantastic science machine!
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This is Dr J signing off for the ESOcast.
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Join me again next time for another cosmic adventure.
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ESOcast is produced by ESO, the European Southern Observatory.
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ESO, the European Southern Observatory, is the pre-eminent intergovernmental science and technology organisation in astronomy
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designing, constructing and operating the world’s most advanced ground-based telescopes.
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The ALMA Project is a partnership between the scientific communities of East Asia, Europe and North America with Chile.
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Transcription by ESO ; translation by —
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Now that you've caught up with ESO,
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head 'out of this world' with Hubble.
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The Hubblecast highlights the latest discoveries of the world's most recognized and prized space observatory,
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the NASA/ESA Hubble Space Telescope